As electronic circuit dimensions decrease, demand for higher densities of active and passive device structures increases. Various nano-fuse structures and their arrangements are known and include, for example, a blowable link having a maximum cross sectional diameter of approximately (±10%) 50 nm and typically approximately 20 nm. The link includes one or more electrically conductive materials and may be blown, for example, by flowing an excessive electrical current through the link. The electrically conductive materials include, for example, metals, metal silicides or conductive (e.g., doped) semiconductors. FIG. 1 shows a schematic circuit diagram of a conventional electrically programmable fuse (eFuse) arrangement, such as a nano-fuse structure connected to a drive transistor, wherein Vdd is approximately three (3) volts and wherein a current I of approximately four (4) ma will blow the link.
Conventional or known fuses, eFuses or nano-fuse structural arrangements are taught, for example, in U.S. Pat. No. 6,624,499 B2, issued Sep. 23, 2003, SYSTEM FOR PROGRAMMING FUSE STRUCTURE BY ELECTROMIGRATION OF SILICIDE ENHANCED BY CREATING TEMPERATURE GRADIENT, by Kothandaraman et al.; U.S. Pat. No. 6,611,039 B2, issued Aug. 26, 2003, VERTICALLY ORIENTED NANO-FUSE AND NANO-RESISTOR CIRCUIT ELEMENTS, by Thomas C. Anthony, and U.S. Pat. No. 7,009,222 B2, issued Mar. 7, 2006, PROTECTIVE METAL STRUCTURE AND METHOD TO PROTECT LOW-K DIELECTRIC LAYER DURING FUSE BLOW PROCESS, by Chao-Hsiang Yang, which are all incorporated in their entireties herein by reference.
During a fuse link blow, metal or other particulate materials are discharged (e.g., blown) from the link and can affect nearby devices or other structures. Also, material in contact or in very close proximity with the fuse link can raise the electrical power or current necessary to blow or break the fuse link.
Several known arrangements to address effects of fuse link blow include, for example: the U.S. Pat. No. 7,009,222 B2 to Yang, which discloses a guard ring comprising a metal interconnect structure surrounding the fuse portion in an uppermost intermetal dielectric (IMD) layer, and the U.S. Pat. No. 6,611,039 B2 to Anthony, which discloses a nano-fuse spacer surrounding an insulating plug which may be voided to provide space for molten or evaporated fuse material to enter. See, for example, col. 5, lines 1-8 of the '039 Patent to Anthony.
Although helpful, these known arrangements in the present inventors' opinions have not proven to be entirely satisfactory because, for example, the present inventors believe portions of the fuse link to be blown remain in intimate physical contact with various materials such as a low k dielectric material.
This intimate physical contact affects the power or current necessary to blow the fuse link, in addition to other drawbacks such as affecting the contacted (e.g. dielectric) layer because of contamination from the particulate and other materials discharged during blow or break of the fuse link.
The present inventors believe these and other drawbacks are overcome in accordance with the present invention.
Therefore, it is a principal object of the present invention to provide a nano-fuse structural arrangement which lowers the electrical power or current necessary to blow or break the fuse link.
It is a further object of the present invention to provide a nano-fuse structural arrangement which reduces adverse effects to devices or other structures surrounding the fuse link caused by materials discharged by fuse link blow.
It is an additional object of the present invention to provide methods of manufacturing and operating such nano-fuse structural arrangements.